Interface is very much like Firefox, only with some superficial enhancements. Firefox users should be comfortable with the interface, which includes the keyboard and context menu shortcuts.

It has a built-in RSS reader (or at least it’s supposed to–it doesn’t work well with my installation), very much like Safari. It’s not an RSS aggregator, though, as it will only switch to viewing the RSS feed of the page you’re currently reading. But very useful, nonetheless, if you prefer reading content only (off with those ads! 😉 )

It has built-in use of the del.icio.us API. So you can share your bookmarks across the web out-of-the-box.

It incorporates the APIs (XML-RPC or Atom or whatever else) of several blogging software so you can blog directly from the browser.

Drag-and-drop multimedia capabilities

Textarea is automatically converted into a rich-text editor. Add this to the drag-and-drop capability, and you have interesting blogpost editing capabilities.

The integrated feed reader is not actually an aggregator. It’s more of an RSS feed viewer. An aggregator would present the user with the option to view multiple feeds from different sources. The integrated viewer in Flock will only display feeds that are present on the current page you’re viewing (ie the posts and comments).

OJ

Flock is so buggy… I will have to wait for the release candidate or the final release to early to evaluate